2015 Chevrolet Corvette Z06 Convertible First Look

These days, Chevrolet engineering is working overtime to eliminate barriers to Corvette ownership. They've replaced its low, flexy, uncomfortable chairs with proper magnesium-framed buckets offering a choice of sport or competition levels of support. The Fisher-Price dash plastics have given way to rich, soft-touch, stitched materials wrapping practically every surface. And now, with the introduction of the Z06, a single Corvette can meet the needs of less-than-identically matched couples. Chief engineer Tadge Juechter explains: "I know many, many customers who, between a couple, couldn't agree on a Z06 because one of the two didn't want a manual transmission or one wanted a convertible for the parade or Friday-night rides or whatever. They just could not agree."

So for 2015, in addition to dialing the Z06's output up to ZR-1 levels (preliminarily rated "at least 625 hp and 635 lb-ft"), the Z06 will be offered with your choice of seven-speed manual or a spanking-new GM-built 8L90 eight-speed torque-converter automatic, in a removable-roof hatchback coupe or one-button convertible soft-top configuration. And just like that, formerly bickering couples can saddle up a Z06 in peace.

"But, Mr. Juechter," you may be fretting, "what if I put the top down and brake-torque that unholy beast? Won't the doors fly open and the car twist one of its rear wheels off the ground like a peeing dog, never to sit flat on all fours again?" Tadge reassures that, while the ragtop Z06 will be the fourth C7 model to hit the road, it's the variant on which all the engineering work was based. "With the big wheels and tires, high braking forces, stiff springs, stiff bars, aggressive shock valving—all those things that contribute to higher loads in the chassis—this is actually the model that drove a lot of the C7's structural requirements in terms of durability, ride comfort, performance, and trackworthiness."

This convertible is 20 percent stiffer than the former fixed-roof Z06 was in torsion. But surely a bolted-in roof would make this new Z06 even more rigid, right? It is true that fastening the removable roof into the hatchback model improves its torsional rigidity by a further 20 percent, but because the new top's latches fasten rigidly in three axes, the bolted-in mounting solution used on the C5 or C6 Z06 wouldn't buy any more rigidity, and raising the soft-top contributes nothing.

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The convertible is every inch a Z06, sharing the hatchback's 10.0 x 19-inch front and 12.0 x 20-inch rear wheels and the wide-body styling needed to envelop them, along with its sport-tuned Magnetic Selective Ride Control shocks and standard electronically controlled multiplate limited-slip differential. The options list is also the same, including the carbon-fiber aero package (front splitter with winglets, rocker panels, and "Gurney flap" on the rear spoiler), and the Z07 performance package (more aggressive splitter and spoiler extension, carbon-ceramic brakes, and Michelin Pilot Sport Cup tires). With the Z07 package, at speed, this convertible body structure is also managing the greatest amount of aero downforce GM has measured on any production car in its wind tunnel. The one-button hydraulic top is identical to the base Stingray's and can be operated at speeds below 30 mph, and the only structural differences are those necessary to mount the top mechanism and relocate the seatbelt anchors.

SAE certification of the 6.2-liter LT4 engine is still pending, but we can expect a single output specification to cover both transmissions and body styles. Juechter believes this will rank as the most power-dense production-car engine from an exterior package envelope standpoint, as this new 1.7-liter Eaton R1740 TVS supercharger packages an inch lower than the ZR-1's 2.3-liter R2300 blower. The new one features shorter rotors that spool up more quickly and spin 5000 rpm faster (20,000 rpm) than the LS9's to flow just as much air. By utilizing direct injection, variable valve timing, and cylinder deactivation, the Z06 is also expected to achieve the best fuel economy in the 600-plus-hp class. (This will be the first supercharged engine to employ cylinder deactivation, but, no, the blower will not make boost in V-4 mode.)

GM's brand-new eight-speed automatic transaxle makes its debut in the Z06, packaging in the same space and (thanks to extensive use of aluminum and magnesium) weighing 8 pounds less than the 6A. The better news is that its broader ratio range (7.01 versus the six-speed's 6.01) and more closely spaced gears keep the engine operating at peak efficiency more of the time, for an expected 5 percent improvement in EPA ratings. Best of all, its shift times are said to be 0.8 second faster than those of a Porsche PDK twin-clutch, so we fully expect the automatic to outrun the manual by a few precious tenths. GM also claims the 8L90 is the highest-capacity transmission ever offered in a Chevy production car, though we question whether it could really withstand more torque than could the mighty and perhaps conservatively rated TurboHydramatic 400.

Lowering the top enhances the visual impact of the broader bodywork, more widely spaced taillamps, and aero graphics, giving the convertible a particularly evil mien. Juechter acknowledges that not everybody will embrace this bigger Z06 tent. "Some hard-core owners liked the idea that it was track-specific, only manual transmission, and you had to be pretty macho to step up and buy one. It created a little bit of an exclusive club. But we are in the business of selling cars to people who love cars, not creating clubs to exclude people." That's a sentiment GM's shareholders and formerly bickering couples can applaud.